Growth and characterization of porcine urinary bladder epithelial cells in vitro

Abstract

Dividing long-term monolayer cultures of porcine urinary bladder epithelial cells were obtained by a combined mechanical and enzymatic isolation method. The serum-free cultured cells were investigated morphologically and characterized according to their growth characteristics and enzymatic functions. Investigations over a period up to 12 wk demonstrated that the cells regain their in vivo polarization with apically situated membrane vesicles and tight junctions between neighboring cells when they have built up a confluent monolayer. Activities of most marker enzymes for cell-differentiated status and function of such cells observed over a period of 4 wk in culture were conserved compared with the original tissue. Lactate dehydrogenase activity release into the medium was at low levels (< or = 5% of the total amount), indicating a good membrane integrity and cell viability. The chromosome set (2n = 38) did not change significantly during the first 5 wk, but, with additional culture time, the degree of polyploid and polynucleated cells increased comparable to the in vivo situation, in which the apical cell layer of the bladder mucosa also showed a high degree of polynucleation and polyploidy, indicative of a senescence process.